Basis for a flexible low-cost automated resistivity data acquisition and analysis system

An efficient and versatile automatic resistivity data acquisition and analysis (ARDAA) system has been developed for use with any 4-electrode output resistivity meter. The acquisition hardware comprises a low-cost Digital Switching Unit (DSU) or an “electronic switch box” which can be interfaced to a portable field microcomputer and a resistivity meter for automatic ground resistivity measurements. Data analysis can be effected in real-time using a simple effective direct inversion scheme that converts each apparent resistivity-electrode spacing data pair into a corresponding effective resistivity-depth information at a rate that is faster than that of acquisition leading to unhindered productivity. The DSU is software programmable thus allowing for easy reconfiguration for the electrode array-type deemed appropriate for a given field survey or for extension to other geophysical techniques where automatic multiple switching is required. Detailed discussions of the system design, practical considerations, time-and cost-savings, and an adaption to the ABEM SAS300 terrameter are provided. A practical evaluation of the infield data-analysis scheme is given and suggestions are offered for extending the basic system for remote-site monitoring applications.